Cable enclosure

ABSTRACT

An enclosure for mounting on a substrate, comprising a rigid tubular support member ( 4 ) and a revolvable elastic sleeve ( 6 ) having a double wall enclosing lubricant ( 14 ) sealed therein, wherein the sleeve is mounted on the support member in an expanded state with a portion of the inner wall of the sleeve secured ( 16 ) to the support member so that the sleeve can be revolved over the end of the support member to contract elastically to a less expanded state while retaining a portion of the sleeve on the support.

[0001] This invention relates to an enclosure, and particularly thoughnot exclusively to one for use with a cable, for example a cable jointor termination.

[0002] The enclosure of the invention finds particular application toelectric, and especially power, cables, but is also applicable to othercables, for example telecommunications cables.

[0003] For convenience only and not by way of limitation, the inventionwill be discussed with reference to an electric power cable joint. Whentwo power cables are to be jointed, the outer layers thereof aresuccessfully stripped back to expose the conductors. The electricalconnection between the conductors is then effected in any convenientmanner. The outer layers of the cables then need to be replaced by freshcomponents in order to restore electrical and mechanical integrity, andthis may be effected in various ways, using various technologies,including tape wrapping. Heat shrink technology, for example using heatrecoverable polymeric sleeves and kits from Tyco Electronics RaychemGmbH, has been known and used successfully for many years, often inpreference to the traditional filling of a casing with hot bitumen orepoxy resin.

[0004] As an alternative to heat-shrinkable sleeves, elastic sleevesthat are recoverable around a cable joint without the application ofheat thereto have been available for some time. One example of such asleeve is that sold by 3M under the tradename PST, which consists of anelastomeric cylindrical sleeve that is held out in an expandedconfiguration by a rigid inner spiral member. These sleeves, mounted ontheir hold-outs, are positioned over the cable joint, and the hold-outis then removed from inside the sleeve. Other elastic sleeves are knownwhich are held out in an expanded configuration on a rigid supportmember with an end of the sleeve folded back on top of the portion ofthe sleeve which is in direct contact with the tubular support, asdescribed by 3M in EP-A-0767523. When the tubular hold-out is positionedover the cable joint, the folded-back portion of the sleeve may berolled over the end of the hold-out to form a bridge that contractselastically down onto the cable. It is observed in EP-A-0767523 that theremoval of the spiral holdouts is problematic and that physical stressrelief adaptations are necessary for the folded-back sleeves.

[0005] WO-A-9113756 describes a revolvable double-wall elastomericsleeve, available from Tyco Electronics Raychem GmbH under the tradenameRAYVOLVE, that has a lubricant enclosed by the double wall of thesleeve. This sleeve, which is not previously expanded, can be rolledonto a cable to one side of the jointing area, which usually involveshaving to increase the sleeve diameter by up to a factor of two or more,and subsequently can be revolved back across the formed joint. Thelubricant facilitates the revolving of the two, inner and outer, wallsof the sleeve over one another. The lubricant remains within the sealeddouble wall of the sleeve, allowing the sleeve to be revolved away andre-used, if the joint needs to be reentered. A RAYVOLVE sleeve isusually employed to provide at least some of the insulation over thecable joint, and may, for example, functionally replace the outer jacketof the cable at the cable joint.

[0006] It is an object of the present invention to provide an improvedenclosure for a substrate. In accordance with one aspect of the presentinvention, there is provided an enclosure for mounting on a substrate,comprising a rigid tubular support member and a revolvable elasticsleeve having a double wall enclosing lubricant sealed therein, whereinthe sleeve is mounted on the support member in an expanded state with aportion of the inner wall of the sleeve secured to the support member sothat the sleeve can be revolved over the end of the support member tocontract elastically to a less expanded state while retaining a portionof the sleeve on the support.

[0007] Thus, the revolvable sleeve is retained attached to the supportmember but is able to be revolved off the member so as to be recoveredto a smaller size around the underlying substrate, in conformitytherewith. The retention of the sleeve at one end on the support memberallows the positioning of the other end of the sleeve on the substrateafter deployment to be controlled, thus ensuring, for a given enclosureand substrate, not only that sufficient overlap onto the substrate isachieved, but also that the sleeve does not roll too far off the supportmember. The revolvable nature of the sleeve inherently facilitatesre-entry of the substrate, for example a cable joint, if required. Theprovision of the support member provides for storage of the sleeve priorto initial installation and also during any re-entry of the substrate.It has been found that the support member may be economicallymanufactured, for example by simply cutting and de-burring suitablelengths from an extruded plastics tube, advantageously omitting anyspecial stress relief adaptations. This advantage may possibly resultfrom the self-reinforcing effect of the double-wall sleeve, whichresists damage at the end regions of the support member more effectivelythat single-wall folded-back sleeves.

[0008] The sleeve may be secured to the support member by any suitablemeans. It is envisaged that this may be by bonding, for example using aninterposed adhesive, and/or by mechanical compression around the outsideof the sleeve, for example using a hose clamp or roll spring, and/or bybeing compressed onto the inner surface of the support member by aninner expandable means. The sleeve may thus conveniently be sealed tothe support member. Typically, the support member is of substantiallyelongate cylindrical shape, with the sleeve being secured to or adjacentone end thereof.

[0009] A further sleeve, similar to the aforementioned sleeve, may bemounted on and secured to the support member, typically providing anarrangement whereby the sleeves can be revolved down off respective endsof the support member onto the substrate, for example a cable each sideof a joint, whilst remaining secured on to the support member by thesaid portions. The or each sleeve is preferably a RAYVOLVE sleeve. Suchsleeves are disclosed in European Patent Application Publication Nos. 0209 399, 0 210 061, 0 210807 and 0 212 851, the entire disclosures ofwhich are incorporated herein by this reference,

[0010] A sealant such as a mastic, may be provided, advantageously onthe substrate or on the sleeve, to seal the sleeve or sleeves to thesubstrate.

[0011] The rigid support member can thus provide mechanical protectionfor the substrate. Advantageously, it is made from a plastics material.The support member may also provide an electrical function, especiallywhen the enclosure surrounds an electric cable. For example, it mayprovide an electrically insulating layer. The support member may be madeof metal, or otherwise be metallic, for example being metallised, andthus may provide electrical continuity or earthing over the substrate,or electrical screening thereof.

[0012] Storing the double-walled lubricated elastic sleeve in anexpanded configuration, on the rigid support member, avoids the need tourge it into an expanded condition as it is revolved up onto asubstrate, such as a cable joint. Unlike known single layer expandedelastic sleeves, the lubricant stays in place, it does not dry out, andit is not exuded from the interface between the sleeve and the supportmember, so that removal of the sleeve from the tubular hold-out memberis facilitated. The sleeve may be expanded to between, say, two and fourtimes its original diameter, thus providing an enclosure, having asuitably sized rigid support member, with a good range-takingcapability. The sleeve can thus be revolved off the support member ontothe substrate with the application of little force, even though itsrubber wall has been stored in a stretched configuration for some time,with the enclosed lubricant having been subjected to high pressure. Theenclosure has a comparatively small overall length, since the sleeve (orsleeves) can be stored thereon within its overall length.

[0013] Embodiments of an enclosure, each in accordance with the presentinvention, will now be described, by way of example, with reference tothe accompanying drawings, in which:

[0014]FIG. 1 is a section through a first embodiment of enclosure priorto its installation over a power cable joint;

[0015]FIG. 2 is a simplified partial section through the installedenclosure of FIG. 1;

[0016]FIG. 3 is a section through a detail of a second enclosure priorto deployment;

[0017]FIG. 4 is a section through the second enclosure in its deployedconfiguration;

[0018]FIG. 5 is section through a detail of a third enclosure prior todeployment; and

[0019]FIG. 6 is section through the third enclosure in its deployedconfiguration.

[0020] Referring to FIGS. 1 and 2, an enclosure 2 comprises a tubularright-cylindrical rigid elongate plastics tube 4. A revolvable RAYVOLVEsleeve 6, which has been expanded to three times its original diameteris mounted on one end 8 of the tube 4. The sleeve 6 has an inner wall 10that lays along the outer surface of the tube 4 and, contiguoustherewith, an outer wall 12. A liquid lubricant 14 is trapped betweenthe walls 10 and 12 of the sleeve 4 so as to allow free revolvingmovement of the sleeve. A strip of adhesive 16 extends around the outercircumference of the tube 4 adjacent its end 8 and serves to secure theinner wall 10 of the sleeve 6 to the tube 4. A further RAYVOLVE sleeve18, substantially identical with the sleeve 6, is similarly secured atthe other end 20 of the tube 4. Components of the sleeve 6 correspondingto those of the sleeve 4 are identified with the addition of thereference “a”.

[0021]FIG. 1 shows the enclosure 2 in its configuration aftermanufacture, with the two RAYVOLVE sleeves 6 and 18 expanded and securedthereto, prior to the mounting of the enclosure 2 on to a substrate.FIG. 2 shows the enclosure 2 of FIG. 1 subsequent to its mounting on asubstrate, which in this embodiment is exemplified as an electricalpower cable joint. Thus, the enclosure 2 is shown in FIG. 2 after it hasbeen mounted so as to encompass a joint region 30 between two electricalpower cables 32 and 34. It will be appreciated that the particularenclosure 2 will have been selected such that the tube 4 has a diameterthat allows it easily to include the joint region 30. Also, theenclosure 2 will have been selected such that the length of the tube 4extends sufficiently beyond the joint region 30.

[0022] Prior to forming the joint between the cables 32 and 34, theenclosure 2 is parked to one side over one of the cables. The jointbetween the conductors of the two cables is made in a convenient manner,for example by means of a crimp, primary insulation is provided aroundthe jointed conductors, and additional insulation and screening asrequired in dependence upon the power rating and structure of the cables32 and 34 is applied. The enclosure 2 is then removed from its parkedposition and centralised over the joint region 30. The RAYVOLVE sleeves6 and 18 are revolved off their respective ends 8 and 20 of the tube 4and allowed to contract down to the outer jackets 36 and 38 respectivelyof the cables 32 and 34. It will be appreciated that the sleeves 6 and18 will be retained on the tube 4 by means of the respective adhesivestrips 16 and 16 a. Furthermore, a sealant 40, 42, is provided so as tolie between the respective sleeves 6 and 18 and the underlying outerjacket 36, 38 of the cables 32 and 34, so as to seal the sleeve 6, 18 onto the respective cable 32, 34. Thus, the enclosure 2 in its recoveredposition, as shown in FIG. 2, provides mechanical protection by means ofits rigid tube 4 around the joint region 30 of the cables, and providessealing on to the cable jackets 36 and 38 at each side thereof. It willbe appreciated that should there be a need to re-enter the joint region30, this may be easily accomplished by rolling the sleeves 6 and 18 backup onto the tube 4 and moving the released enclosure 2 to one side,thereby leaving the enclosure 2 available for re-use.

[0023] The enclosure of the first embodiment has been described with therevolvable sleeves 6 and 18 secured to the plastics tube 4 by beingbonded thereto, using an adhesive 16, 16 a respectively. It isenvisaged, however, that the or each revolvable sleeve may be secured tothe support member alternatively, or additionally, by a mechanicalclamping means, which need not require the formation of a bond.Arrangements of such enclosures are shown in FIGS. 3 to 6, which show adetail only of the securement of the revolvable sleeve to the supportmember, other features of these enclosures may correspond to thosedisclosed above.

[0024] Referring to FIGS. 3 and 4, a generally circular hose clamp 50 islocated around one end 52 of a revolvable sleeve 54, adjacent one end 56of a rigid cylindrical plastics tube 58. As with the enclosure of thefirst embodiment, the enclosure formed thereby is mounted over asubstrate and the sleeve 54 is revolved over the end 56 of the tube 58into the deployed position as shown in FIG. 4, with the sleeve end 52clamped around its outer surface to the tube 58 by the hose 50. It willthus be appreciated that the inwardly-directed compression of the hoseclamp 50 retains the sleeve 54 on the tube 58 at all times.

[0025] In a further embodiment of a clamping means shown in FIGS. 5 and6, one end 70 of a revolvable sleeve 72 is folded inwardly over one end74 of a cylindrical rigid plastics tube 76 and is held in place by aspiral spring 78 located around the inner circumference thereof. It willbe appreciated that the spring 78 has a tendency to uncoil outwards andthereby compresses the end 70 of the sleeve 72 against the innercircumference of the end 74 of the tube 76. The remaining length 80 ofthe sleeve 72 lies along the outer surface of the tube 76. To preventany tendency of the sleeve portion 80 to revolve off the tube 76 of itsown accord, an outer circumferential fixing device 82 is locatedtherearound at the opposing end 84 of the sleeve 72. The fixing device82 may conveniently be breakable by hand, whereby the sleeve portion 80may be revolved over the outer surface of the tube 76 and deployed downonto the substrate, as can be seen from FIG. 6. Advantageously, breakingof the fixing device 82 may trigger self-deployment of the sleeve 72down onto the substrate.

1. An enclosure for mounting on a substrate, comprising a rigid tubularsupport member and a revolvable elastic sleeve having a double wallenclosing lubricant sealed therein, wherein the sleeve is mounted on thesupport member in an expanded state with a portion of the inner wall ofthe sleeve secured to the support member so that the sleeve can berevolved over the end of the support member to contract elastically to aless expanded state while retaining a portion of the sleeve on thesupport.
 2. An enclosure according to claim 1, wherein the supportmember is of substantially elongate cylindrical shape, and the sleeve issecured thereto in the region of one end thereof.
 3. An enclosureaccording to claim 2, comprising a further double-walled elastic sleevehaving lubricant sealed therein, the further sleeve being mounted on thesupport member in an expanded configuration with a portion of its innerwall secured to the support member in the region of the other endthereof.
 4. An enclosure according to any one of the preceding claims,wherein the or each sleeve is secured to the support member by adhesive.5. An enclosure according to any one of the preceding claims, whereinthe or each sleeve is secured to the support member by a clamping means.6. An enclosure according to any one of the preceding claims, whereinthe support member is made of a plastics material.
 7. An arrangementcomprising a substrate located within an enclosure according to any oneof the preceding claims, wherein the or each sleeve has been revolvedalong the support member and contracted onto the substrate.
 8. Anarrangement according to claim 7, wherein a further portion of the innerwall of the or each sleeve is sealed on to the substrate.
 9. Anarrangement according to claim 7 or 8, wherein the substrate comprisesan electric cable, preferably a cable joint or cable termination.
 10. Anarrangement according to claim 9, wherein the support member provideselectrical screening of the cable.